Ophthalmic procedures are typically performed with instruments that have a tip located at the distal end of a handpiece. The handpiece is held by a surgeon who inserts the tip into the inner ocular chamber of an eye. By way of example, the surgeon may remove a cataracteous lens, or reattach a retina with the instrument.
During a procedure, irrigation fluid is introduced into the eye to maintain the ocular pressure of the anterior chamber. The handpiece tip is coupled to an aspiration system that pulls the irrigation fluid and possibly tissue out of the anterior chamber. The tissue and irrigation fluid flow through an inner channel in the tip.
The aspiration system includes a pump coupled to an aspiration tube. The aspiration tube is connected to an outlet port of the handpiece. Most aspiration pumps are of the peristaltic type because the pump behavior is predictable. A peristaltic pump essentially pushes the air/fluid within the aspiration tube to create, a vacuum pressure within the tube. The operation of a peristaltic pump creates surges in the pressure within the system. Pressure surges can be undesirable when performing delicate procedures such as retinal reattachment.
Some aspiration systems contain a venturi type pump. Venturi pumps do not create pressure surges and are thus typically used in delicate ophthalmic procedures. Commercially available venturi pumps require a tank of compressed nitrogen gas. It is generally undesirable to have a pressurized gas tank in an operating environment. Additionally, venturi pumps are energy inefficient in creating a vacuum.